OK guy i have an 08 yz450 with a powercore 4 slip on and stock header. with all the research Ive done sound like the 08-09 stock header is way to big for what i use the bike for which is mx. So a buddy of mine had an extra DRD header when i went to put it on i noticed that the PC4 mid pipe is bigger than the DRD. so i called fmf to see if the make a sleeve and the do but what i wanted to see if any one on here know if will work. FMF said i would need the sleeve for a Powerbomb header with the PC4. so if any one on here knows if they are the same dimensions. or if they could measure there powerbomb header for me that would be great. I dont want to buy a $25 sleeve and it not work. Thank guys.